The invention relates to a spinning apparatus for melt spinning and cooling endless synthetic multifilament yarns.
In the production of synthetic multifilament yarns, a molten polymer is extruded to a plurality of strandlike filaments. To this end, the polymer melt is advanced by means of a pump via lines to one or more spin packs. Besides filter and distributor elements, the spin packs comprise a spinneret with a plurality of bores. The pump, lines, and spin packs are accommodated in a heated spin head. After cooling the filaments, which are extruded through the bores of the spinneret, by means of a cooling device, for example an air stream, the filament bundles are combined to respectively one yarn, and the yarn undergoes further treatment. In most cases a spin head accommodates four, six, or more spin packs in a narrowly spaced relationship in one row.
It has been found advantageous to guide the air stream that cools the filaments, together with the filaments and parallel to the filaments, at a high flow velocity through a cooling tube. An apparatus for carrying out such a method is described, for example, in WO 99/067450 and corresponding U.S. Patent Application Publication 2001/0033037. In this apparatus, a suction fan is provided at the end of the cooling tube for maintaining the required flow velocity. At the upper end of the cooling tube, the cooling air is supplied to the cooling tube through a screen cylinder.
In this connection, the need arises for sealing the connection from the cooling tube to the spin head against ambient air in a separable manner for purposes of avoiding the inflow of secondary air. In so doing, it should be noted that the spinnerets accommodated in the spin packs are arranged in a very narrowly spaced relationship. The reason therefore lies on the one hand in that the available assembly space in the spin head is limited. On the other hand, the spinnerets and the spin packs connected thereto have a large diameter, in particular in the case large numbers of filaments.
DE 34 06 347 A1 discloses a possibility of sealingly connecting a cooling tube with an air chamber surrounding it to the spin head such that the cooling tube and the air chamber can be lowered for servicing procedures. To this end, DE 34 06 347 A1 provides on the side of the spin head and on the side of the cooling tube flanges, between which a sealing means and a heat insulating means are provided. The heat insulating means prevents heat from flowing out of the spin head into the spin shaft. The sealing means interconnects the spin head and the cooling tube in an airtight manner, and it is designed and constructed for separation.
Because of the flanges on the spin head side, the teaching described in DE 34 06 347 A1 cannot be applied to spin heads with spin packs arranged in a very narrowly spaced relationship. On the other hand, impermeability to gas between spin head and spin pack is not ensured in all types of spin heads. In such a case, cooling air would be pulled through the spin head, and the latter be cooled in an unacceptable manner.
It is therefore an object of the invention to further develop the seal between the spin head and the cooling tube such that a seal can also be used in spin heads with spin packs arranged in a very narrowly spaced relationship, as well as in types of spin heads, which are not made gastight between the spin head and the spin pack.
In accordance with the invention, the above and other objects are achieved in that a separating plane of the sealing unit located on the side of the spin head is arranged on the spin pack.
As a result of the invention, it is possible to realize a cooling device in alignment with a filament bundle even in the case of very compact spin heads with a correspondingly narrow spacing between the spin packs. The separation between the spin pack and the cooling tube is sealed by the sealing unit in an advantageous manner against secondary air, with the sealing unit also covering the underside of the spin pack. Both the separating plane on the spin head side and the separating plane on the cooling tube side are configured such that after each separation, the impermeability of the sealing unit remains substantially unchanged. The sealing unit is understood to include all means, which are necessary to connect a cooling tube to a spin pack in a sealable manner.
A special advantage of the invention lies in that the cooling tubes are constructed with a smaller diameter and, thus, can also be arranged in a narrowly spaced relationship, and that the sealing unit may be used even in spin heads that are not gastight.
To arrange the spin packs inside the spin head with the smallest possible spacing between one another for a particularly narrow spacing between the spinning positions, it is preferred to design and construct the spinning apparatus of the present invention with the sealing unit being located substantially within the peripheral boundary that is defined by the cross section of the spin pack.
In another advantageous further development of the invention, the separating plane located on the spin head side is arranged directly on the spinneret. This permits the realization of still narrower dimensions of the spacing in comparison with the above described construction.
In a particularly advantageous further development of the invention, the separating plane on the spin head side is arranged on a fastening member for the spin pack or on a fastening member for the spinneret. This allows further assembly space to be saved, and to achieve an especially narrow spacing between the spin packs.
To permit the sealing unit between the spin pack and the cooling tube to be removed as far as possible from the underside of the spin pack, it is possible to arrange the separating plane on the spin head side on an end face of an annular collar which projects from the underside of the spin pack. This reduces the inflow of heat from the spin pack into the sealing unit to a great extent, so that the sealing unit need not have a resistance to extreme temperatures.
Advantageously, the separating plane arranged on the cooling side is formed directly on the end of the cooling tube facing the spin head.
However, in many cases it is necessary that no significant amount of heat be removed from the spin pack or spinneret via the connection to the cooling tube. This would lower the temperature of the melt in a disadvantageous manner. For this reason, an advantageous further development of the invention provides for a thermal separation of the cooling tube. This occurs by insulating the sealing unit against heat.
According to a particularly advantageous further development of the invention, the insulating and sealing functions may be separated from each other. To this end, the sealing unit comprises an insulating member for the heat insulation, and a separate sealing element for the sealing.
In a particularly favorable embodiment, the insulation is arranged on the heated side, i.e., in facing relationship with the spin head. This permits lowering the temperature level of the seal, so that it is also possible to use temperature sensitive materials for the seal. The temperature level of the seal can be further lowered by placing a heat dissipating member between the insulation and the seal.